|
(11) | EP 1 358 297 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
|
|
| (54) |
USE OF A ZWITTERIONIC SURFACTANT TOGETHER WITH AN ANIONIC ETHER-CONTAINING SURFACTANT AS A DRAG-REDUCING AGENT VERWENDUNG EINES ZWITTERIONISCHEN TENSIDS ZUSAMMEN MIT EINEM ANIONISCHEN ETHERHALTIGEN TENSID ALS STRÖMUNGSBESCHLEUNIGER UTILISATION COMME AGENT DE REDUCTION DE TRAINEE D'UN TENSIO-ACTIF ZWITTERIONIQUE EN COMBINAISON AVEC UN TENSIO-ACTIF ANIONIQUE CONTENANT DE L'ETHER |
|
|
|||||||||||||||||||||||||||||||
| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] The present invention relates to the use of a zwitterionic surfactant together with an ether sulphate or ether carboxylate surfactant in a water-based system as a drag-reducing agent.
[0002] Surfactants with the ability to form extremely long, cylindrical micelles have, in recent years, attracted a great interest as drag-reducing additives to systems with circulating water, especially those destined for heat or cold distribution.
[0003] An important reason for this interest is that, although one desires to maintain a laminar flow in the conduits, one wishes at the same time to have turbulence in the heat exchangers to achieve therein a high heat transfer per unit area.
[0004] As may easily be understood, fibres or chain polymers are unable to provide this double function which, however, can be achieved with thread-like micelles, since the micelles, which are responsible for the drag reduction, can be destructed by mechanical devices either within the heat exchangers or immediately before them. Thus a turbulent flow will be created within said heat exchangers. In the tube after the exchanger the micelles will form again rather rapidly and the drag reduction will thus be restored.
[0005] The thread-like micelles are distinguished by operating in a fairly disorderly fashion at low Reynold's numbers (below 104), having no or only a very slight effect on the flow resistance. At higher Reynold's numbers (above 104), the micelles are paralleled and result in a drag reduction very close to that which is theoretically possible. At even higher Reynold's numbers (e.g. above 105) the shear forces in the liquid become so high that the micelles start to get torn and the drag-reducing effect rapidly decreases as the Reynold's number increases above this value.
[0006] The range of Reynold's numbers within which the surface-active agents have a significant drag-reducing effect is dependent on the concentration, the range increasing with the concentration.
[0007] By choosing the right concentration of surface-active agents and suitable flow rates in conduits and adequate devices before or in the heat exchangers, it is thus possible to establish a laminar flow in the conduits and turbulence in the heat exchangers. Thus, the dimensions of the conduits can be kept at a low level and the pump size, or the number of pump stations, and consequently the pump work, can alternatively be reduced while retaining the same tubular dimensions.
[0008] In WO 96/28527 a drag reducing agent is disclosed, which comprises a betaine surfactant in combination with a sulphonate or sulphate surfactant. This drag-reducing agent is effective within comparatively large temperature ranges. However, the sulphate surfactant is rather sensitive to hard water, while the sulphonate surfactant is not regarded as easily biodegradable under anaerobic conditions. Document US-A-5 902 784 discloses the use of a betaine surfactant together with an anionic surfactant as a drag-reducing agent. As zwitterionic surfactant, CH3(CH2)15 - N+ (CH3)2 - CH2COO- is used, together with a sodium salt of a linear dodecylbenzenesulphonate.Document US-A-5 902 784 discloses the use of a betaine surfactant together with an anionic surfactant as a drag-reducing agent. As zwitterionic surfactant, CH3(CH2)15 - N+ (CH3)2 - CH2COO- is used, together with a sodium salt of a linear dodecylbenzenesulphonate.
[0009] It has now surprisingly been found that essential improvements are achieved by the use of a zwitterionic surfactant having the formula
R is a group containing saturated or unsaturated aliphatic or acyl group with 10-24 carbon atoms, R6 and R7 are independently of each other an alkyl group of 1-4 carbon atoms or an hydroxyalkyl group of 2-4 carbon atoms, and R4 is an alkylene group of 1-4 carbon atoms, preferably CH2 or a group
where R5 is an alkyl group of 1-3 carbon atoms, in combination with an anionic ether surfactant having the general structure
R1(OA)nB, R1O(AO)nCmH2mD or R3NH(AO)nCmH2mD
or a mixture thereof, where R1 is a hydrocarbon group of 10-24 carbon atoms, R3 is an acyl group of 10-24 carbon atoms, A is an alkylene group having 2-4 carbon atoms, n is a number from 1 to 10, m is 1-4, B is a sulphate group OSO3M, D is a carboxylate group COOM, and M is a cationic, preferably monovalent group, in a weight proportion between the zwitterionic surfactant and the anionic ether surfactant or ether surfactants of from 100:1 to 1:1, preferably from 50:1 to 2:1, as a drag-reducing agent in a flowing water-based liquid system. By "water-based" is meant that at least 50% by weight, preferably at least 90% by weight, of the water-based liquid system consists of water. The total amount of the zwitterionic surfactant and the anionic ether surfactants may vary within wide limits depending on the conditions but is generally 0.1-10 kg/m3 of the water-based system. The combinations of the zwitterionic and the anionic ether surfactants are especially suited for use in water-based systems flowing in long conduits, for distribution of heat or cold.
[0010] The group R in the zwitterionic surfactant is suitably an aliphatic group or a group R'NHC3H6, where R' designates an acyl group with 10-24 carbon atoms. Preferably the zwitterionic surfactant has the general formula
where R is the aliphatic group or the group R'NHC3H6- where R' has the meaning mentioned above. In the anionic ether surfactant the hydrophobic group R1 can be aliphatic or aromatic, straight or branched, saturated or unsaturated. Furthermore, the groups A are preferably ethylene, n is preferably a number from 1-5 and CmH2m is preferably methylene or the group
where R8 is an alkyl group of 1-3 carbon atoms. The group M is preferably sodium and potassium.
[0011] Both the zwitterionic surfactant and the anionic ether surfactants are readily biodegradable and tolerant towards hard water and electrolytes and said combination gives an excellent drag reducing effect within a wide temperature range. Thus, the drag-reducing additives may be used in a cooling media at temperatures below 20°C, when using surfactants, where the groups R and R' have 12-16 carbon atoms, and in a heat-transfer medium at a temperature in the range of 50-120°C, when using surfactants where the groups R, and R' contain 18, 20 or 22 carbon atoms or more. The number of carbon atoms in the hydrophobic groups R, R', R1 and R3 will affect the useful temperature range for the mixture so that a high number will give products suitable for high temperatures and vice versa. The groups R and R1 can suitably be dodecyl, tetradecyl, hexadecyl, octadecyl, oleyl, eicosyl, docosyl, rape seed alkyl and tallow alkyl and the groups R' and R3 the corresponding acyl groups. Also aromatic groups, such as nonylphenol, may be used.
[0012] Furthermore, the zwitterionic and anionic surfactants are suitably chosen in such a manner that the crystallisation temperature for the combination is suitably below the lowest temperature for which the water-based system is intended. Suitably the zwitterionic surfactant is combined with an anionic ether sulphate surfactant where n is 1-5 and OA oxyethylene, since the ether sulphate is easy to produce and gives in combination with the zwitterionic surfactant excellent drag-reducing effects.
[0013] The zwitterionic surfactant can be produced by reacting a compound of the formula RNR6R7, where R has the meaning mentioned above, with Na-chloroacetate at 70-80°C and a constant pH-value of 9.5 in a medium of a lower alcohol and water. To obtain a good drag reducing effect it is essential that the amount of the amine reactant in the zwitterionic product used is low. If a low chloride content in the product is necessary the reaction can preferably be made in isopropanol with the lowest water content possible, whereby the sodium chloride formed in the reaction will crystallise out of the product and may be removed by filtration or centrifugation. Another route to a chloride-free product is to quaternize the amine reactant with ethylene oxide in the presence of an acid catalyst and then dehydrogenate the resulting product to the desired zwitterionic surfactant.
[0014] The anionic ether surfactants suitable for use in accordance with the invention are well-known products and so are also the production methods. Typical examples are aliphatic mono(oxyethylene) sulphates, alkyl di(oxyethylene) sulphates and alkyl tri(oxyethylene) sulphates derived from ethoxylated alcohols by sulphation with SO3 and the corresponding carboxylates obtained by reacting said ethoxylated alcohol and a halogenated carboxylate having the formula HalCmH2mCOOM, where Hal is chloride or bromide and M and m have the meanings mentioned above. The amido ether carboxylate may be produced according to well-known methods including the reaction of said halogenated carboxylate and the amidoalkoxylate R3NH(AO)nH, where R3, A and n have the meanings mentioned above.
[0015] The choice of the zwitterionic surfactant and the anionic ether surfactant will depend of the temperature of the water-based system. At low temperature the number of carbon atoms will normally be lower than at high temperature while the number of oxyalkylene will normally be higher at lower temperatures than at higher temperatures.
[0016] A convenient way to determine the right proportion between the zwitterionic surfactant and the anionic surfactant for a certain type of water is to make up a solution of e.g. 0.500 kg/m3 of the zwitterionic surfactant in the appropriate water in a 50 ml glass beaker with a magnetic stirrer and keep the temperature in the middle of the intended temperature range for the system. This solution is then titrated with a solution of the anionic ether surfactant with a concentration of 10 kg/m3 in the appropriate water until the originally formed vortex has disappeared.
[0017] Apart from the zwitterionic and anionic surfactant, the water-based system may contain a number of conventional components such as corrosion inhibitors, anti-freeze and bactericides.
[0018] The present invention will now be further illustrated with the aid of the following examples.
Example 1
[0019] The drag reducing temperature interval was determined in the beaker test described above. In the beaker test the surfactant mixture was stirred at a constant rotation speed of 700 r/min using a combined magnetic stirrer and heating plate. The absence of vortex or a vortex of max. 2 mm was equal to drag reducing conditions. In temperatures above 100°C a glass pressure reactor was used.
[0020] From stock solutions mixtures of betaine and anionic surfactant were prepared. The mixtures were diluted with water, with hardness according to the tables below, to 1000 ppm betaine and a total volume of 40 ml in a 50 ml beaker. The amount of anionic surfactant is given as ppm in brackets. The pH was adjusted to 9-10 with ammonia.
Table 1. N-behenyl betaine (1000 ppm) for heating systems
| Anionic surfactant | DR interval (700 r/min) | |||||
| 0 °dH | 3 °dH | 8 °dH | ||||
| Sodium dodecyl sulphate | 55-120 | (30) | 55-68 | (30) | 55-68 | (30) |
| Sodium dodecyl-(EO)3- sulphate | 55-123 | (40) | 55-108 | (40) | 50-78 | (40) |
| Dodecyl amide-(EO)2- carboxylate | 55-104 | (40) | 48-95 | (40) | 49-86 | (40) |
| Nonylphenol-(EO)3- carboxylate | 53-97 | (40) | 49-94 | (40) | 49-74 | (40) |
[0021] A drag reducing agent containing an anionic ether surfactant exhibit an essentially better drag reducing effect in water of 3 °dH and 8 °dH than the agent containing alkyl sulphate.
Example 2
[0023] In order to determine the right amount of anionic surfactant the betaine solution was kept at 13°C in the test beaker with the magnetic stirrer running at 700 r.p.m and titrated with a water solution of the anionic surfactant until the vortex disappeared. The resulting concentration of anionic surfactant is given as ppm in brackets after the temperature range within which the composition has been found to give a drag reducing effect. The clear point (CP) of the solution is given in °C.
[0024] The concentration of the N-myristyl-betaine, the zwitterionic surfactant used in this example, was 1000 ppm in all tests.
Table 2. N-myristyl-betaine (1000 ppm) in mixture with anionic surfactant for cooling
systems
| Anionic surfactant | DR interval (700r/min) | ||
| 0 °dH | 3 °dH | 8 °dH | |
| Dodecyl benzene sulphonate | No effect (0-1130) CP 0°C |
0-29 (430) CP 0°C |
3-25 (980) CP 35°C |
| Sodium dodecyl-(EO)3- sulphate | 0-43 (288) CP 0°C |
0-27 (550) CP 0°C |
2-25 (510) CP 2°C |
| Sodium dodecyl sulphate | 6-43 (400) CP 6°C |
0-39 (336) CP 14°C |
4-43 (360) CP 20°C |
[0025] These formulations are intended for comfort cooling circuits where the temperature range normally is between 4 and 15°C.
1. Use of a zwitterionic surfactant having the formula
R is a group containing a saturated or unsaturated aliphatic or acyl group with 10-24 carbon atoms, R6 and R7 are independently of each other an alkyl group of 1-4 carbon atoms or an hydroxyalkyl group of 2-4 carbon atoms, and R4 is an alkylene group of 1-4 carbon atoms, in combination with an anionic ether surfactant having the general structure
R1(OA)nB, R1O(AO)nCmH2mD or R3NH(AO)nCmH2mD
or a mixture thereof, where R1 is a hydrocarbon group of 10-24 carbon atoms, R3 is an acyl group of 10-24 carbon atoms, A is an alkylene group having 2-4 carbon atoms, n is a number from 1 to 10, m is 1-4, B is a sulphate group OSO3M and D is a carboxylate group COOM, in which M is a cationic group, in a weight proportion between the zwitterionic surfactant and the anionic ether surfactant or ether surfactants of from 100:1 to 1:1 as a drag-reducing agent in a flowing water-based liquid system.
R is a group containing a saturated or unsaturated aliphatic or acyl group with 10-24 carbon atoms, R6 and R7 are independently of each other an alkyl group of 1-4 carbon atoms or an hydroxyalkyl group of 2-4 carbon atoms, and R4 is an alkylene group of 1-4 carbon atoms, in combination with an anionic ether surfactant having the general structure
R1(OA)nB, R1O(AO)nCmH2mD or R3NH(AO)nCmH2mD
or a mixture thereof, where R1 is a hydrocarbon group of 10-24 carbon atoms, R3 is an acyl group of 10-24 carbon atoms, A is an alkylene group having 2-4 carbon atoms, n is a number from 1 to 10, m is 1-4, B is a sulphate group OSO3M and D is a carboxylate group COOM, in which M is a cationic group, in a weight proportion between the zwitterionic surfactant and the anionic ether surfactant or ether surfactants of from 100:1 to 1:1 as a drag-reducing agent in a flowing water-based liquid system.
2. Use according to claim 1, where the zwitterionic surfactant has the general formula
where R is the aliphatic group or the group R'NHC3H6- where R' is the acyl group.
where R is the aliphatic group or the group R'NHC3H6- where R' is the acyl group.
3. Use as claimed in claim 1 or 2, characterised in that the crystallisation temperature for the combination is below the lowest temperature
in the flowing water-based system.
4. Use as claimed in any one of claims 1-3, characterised in that the zwitterionic surfactant and anionic ether surfactant is added in a total amount
of 0.1-10 kg/m3 of the water-based system.
5. Use as claimed in claim 1, 2, 3 or 4, characterised in that the water-based system is a heat-transfer medium with a temperature in the range
of 50-120°C.
6. Use as claimed in claim 1, 2, 3 or 4, characterised in that the water-based system is a cooling medium with a temperature below 20°C.
7. Use as claimed in any one of claims 1-5, characterised in that the groups R and R' contain 18-24 carbon atoms.
8. Use as claimed in any one of claims 1-4 and 6, characterised in that the group R, and R1 contain 12-16 carbon atoms.
9. Use as claimed in any one of claims 1-8 characterised in that the groups R4 and CmH2m designate ethylene.
10. Use as claimed in any one of claims 1-9, characterised in that the anionic ether surfactant is an ether sulphate, where n is 1-5 and OA is oxyethylene.
1. Verwendung eines zwitterionischen Tensids mit der Formel
wobei R eine Gruppe ist, die eine gesättigte oder ungesättigte aliphatische oder Acylgruppe mit 10 bis 24 Kohlenstoffatomen enthält, R6 und R7 unabhängig voneinander eine Alkylgruppe mit 1 bis 4 Kohlenstoffatomen oder eine Hydroxyalkylgruppe mit 2 bis 4 Kohlenstoffatomen sind und R4 eine Alkylengruppe mit 1 bis 4 Kohlenstoffatomen ist, in Kombination mit einem anionischen Ether-Tensid mit der allgemeinen Struktur
R1(OA)nB, R1O(AO)nCmH2mD oder R3NH(AO)nCmH2mD
oder einem Gemisch davon, wobei R1 eine Kohlenwasserstoffgruppe mit 10 bis 24 Kohlenstoffatomen ist, R3 eine Acylgruppe mit 10 bis 24 Kohlenstoffatomen ist, A eine Alkylengruppe mit 2 bis 4 Kohlenstoffatomen ist, n eine Zahl von 1 bis 10 ist, m = 1 bis 4 ist, B eine Sulfatgruppe OSO3M ist und D eine Carboxylatgruppe COOM ist, wobei M eine kationische Gruppe ist, in einem Gewichtsverhältnis zwischen dem zwitterionischen Tensid und dem oder den anionischen Ether-Tensiden von 100:1 bis 1:1 als Strömungsbeschleuniger in einem auf fließendem Wasser beruhenden Flüssigkeitssystem.
wobei R eine Gruppe ist, die eine gesättigte oder ungesättigte aliphatische oder Acylgruppe mit 10 bis 24 Kohlenstoffatomen enthält, R6 und R7 unabhängig voneinander eine Alkylgruppe mit 1 bis 4 Kohlenstoffatomen oder eine Hydroxyalkylgruppe mit 2 bis 4 Kohlenstoffatomen sind und R4 eine Alkylengruppe mit 1 bis 4 Kohlenstoffatomen ist, in Kombination mit einem anionischen Ether-Tensid mit der allgemeinen Struktur
R1(OA)nB, R1O(AO)nCmH2mD oder R3NH(AO)nCmH2mD
oder einem Gemisch davon, wobei R1 eine Kohlenwasserstoffgruppe mit 10 bis 24 Kohlenstoffatomen ist, R3 eine Acylgruppe mit 10 bis 24 Kohlenstoffatomen ist, A eine Alkylengruppe mit 2 bis 4 Kohlenstoffatomen ist, n eine Zahl von 1 bis 10 ist, m = 1 bis 4 ist, B eine Sulfatgruppe OSO3M ist und D eine Carboxylatgruppe COOM ist, wobei M eine kationische Gruppe ist, in einem Gewichtsverhältnis zwischen dem zwitterionischen Tensid und dem oder den anionischen Ether-Tensiden von 100:1 bis 1:1 als Strömungsbeschleuniger in einem auf fließendem Wasser beruhenden Flüssigkeitssystem.
2. Verwendung gemäß Anspruch 1, wobei das zwitterionische Tensid die allgemeine Formel
hat, wobei R die aliphatische Gruppe oder die Gruppe R'NHC3H6-, wobei R' die Acylgruppe ist, ist.
hat, wobei R die aliphatische Gruppe oder die Gruppe R'NHC3H6-, wobei R' die Acylgruppe ist, ist.
3. Verwendung gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Kristallisationstemperatur für die Kombination unter der niedrigsten Temperatur
des auf fließendem Wasser beruhenden Systems liegt.
4. Verwendung gemäß Anspruch 1 bis 3, dadurch gekennzeichnet, dass das zwitterionische Tensid und das anionische Ether-Tensid in einer Gesamtmenge von
0,1 bis 10 kg/m3 des auf Wasser beruhenden Systems hinzugefügt werden.
5. Verwendung gemäß Anspruch 1, 2, 3 oder 4, dadurch gekennzeichnet, dass das auf Wasser beruhende System ein Wärmeübertragungsmittel mit einer Temperatur
im Bereich von 50 bis 120°C ist.
6. Verwendung gemäß Anspruch 1, 2, 3 oder 4, dadurch gekennzeichnet, dass das auf Wasser beruhende System ein Kühlmittel mit einer Temperatur von unter 20°C
ist.
7. Verwendung gemäß einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass die Gruppen R und R' 18 bis 24 Kohlenstoffatome enthalten.
8. Verwendung gemäß einem der Ansprüche 1 bis 4 und 6, dadurch gekennzeichnet, dass die Gruppen R' und R1 12 bis 16 Kohlenstoffatome enthalten.
9. Verwendung gemäß einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass die Gruppen R4 und CmH2m Methylen bezeichnen.
10. Verwendung gemäß einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass das anionische Ether-Tensid ein Ethersulfat ist, wobei n = 1 bis 5 ist und OA = Oxyethylen
ist.
1. Utilisation d'un tensioactif zwitterionique de formule
R est un groupe contenant un groupe aliphatique ou acyle saturé ou insaturé contenant 10 à 24 atomes de carbone, R6 et R7 sont indépendamment l'un de l'autre un groupe alkyle contenant 1 à 4 atomes de carbone ou un groupe hydroxyalkyle contenant 2 à 4 atomes de carbone, et R4 est un groupe alkylène contenant 1 à 4 atomes de carbone, en combinaison avec un tensioactif anionique éthéré de structure générale R1(OA)nB, R1O(AO)nCmH2mD ou R3NH(AO)nCn,H2n,D ou un de leurs mélanges, où R1 est un groupe hydrocarboné contenant 10 à 24 atomes de carbone, R3 est un groupe acyle contenant 10 à 24 atomes de carbone, A est un groupe alkylène contenant 2 à 4 atomes de carbone, n est un nombre allant de 1 à 10, m est 1 à 4, B est un groupe sulfate OSO3M et D est un groupe carboxylate COOM où M est un groupe cationique, en une proportion en poids entre le tensioactif zwitterionique et le tensioactif anionique éthéré ou d'autres tensioactifs éthérés de 100 : 1 à 1 : 1, comme agent de réduction de traînée dans un système liquide à base d'eau en écoulement.
R est un groupe contenant un groupe aliphatique ou acyle saturé ou insaturé contenant 10 à 24 atomes de carbone, R6 et R7 sont indépendamment l'un de l'autre un groupe alkyle contenant 1 à 4 atomes de carbone ou un groupe hydroxyalkyle contenant 2 à 4 atomes de carbone, et R4 est un groupe alkylène contenant 1 à 4 atomes de carbone, en combinaison avec un tensioactif anionique éthéré de structure générale R1(OA)nB, R1O(AO)nCmH2mD ou R3NH(AO)nCn,H2n,D ou un de leurs mélanges, où R1 est un groupe hydrocarboné contenant 10 à 24 atomes de carbone, R3 est un groupe acyle contenant 10 à 24 atomes de carbone, A est un groupe alkylène contenant 2 à 4 atomes de carbone, n est un nombre allant de 1 à 10, m est 1 à 4, B est un groupe sulfate OSO3M et D est un groupe carboxylate COOM où M est un groupe cationique, en une proportion en poids entre le tensioactif zwitterionique et le tensioactif anionique éthéré ou d'autres tensioactifs éthérés de 100 : 1 à 1 : 1, comme agent de réduction de traînée dans un système liquide à base d'eau en écoulement.
2. Utilisation selon la revendication 1, dans laquelle le tensioactif zwitterionique
est de formule générale
dans laquelle R est le groupe aliphatique ou le groupe R'NHC3H6- où R' est le groupe acyle.
dans laquelle R est le groupe aliphatique ou le groupe R'NHC3H6- où R' est le groupe acyle.
3. Utilisation selon la revendication 1 ou 2, caractérisée en ce que la température de cristallisation pour la combinaison est inférieure à la température
la plus basse du système à base d'eau en écoulement.
4. Utilisation selon l'une quelconque des revendications 1 à 3, caractérisée en ce que le tensioactif zwitterionique et le tensioactif anionique éthéré sont ajoutés en
une quantité totale de 0,1 à 10 kg/m3 du système à base d'eau.
5. Utilisation selon la revendication 1, 2, 3 ou 4, caractérisée en ce que le système à base d'eau est un milieu de transfert de chaleur ayant une température
située dans la plage allant de 50°C à 120°C.
6. Utilisation selon la revendication 1, 2, 3 ou 4, caractérisée en ce que le système à base d'eau est un milieu de refroidissement ayant une température inférieure
à 20°C.
7. Utilisation selon l'une quelconque des revendications 1 à 5, caractérisée en ce que les groupes R, et R' contiennent 18 à 24 atomes de carbone.
8. Utilisation selon l'une quelconque des revendications 1 à 4 et 6, caractérisée en ce que le groupe R et le groupe R1 contiennent 12 à 16 atomes de carbone.
9. Utilisation selon l'une quelconque des revendications 1 à 8, caractérisée en ce que les groupes R4 et CmH2m désignent le méthylène.
10. Utilisation selon l'une quelconque des revendications 1 à 9, caractérisée en ce que le tensioactif anionique éthéré est un éthersulfate, où n est 1 à 5 et OA est l'oxyéthylène.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description